1. Field
The present disclosure relates to genetically engineered bacteria cells having an enhanced activity of GlnD or GlnK, and methods of producing succinic acid by using the genetically engineered bacteria cells.
2. Description of the Related Art
Corynebacterium genus microorganisms as a class of gram-negative strains are widely in use for the production of amino acids such as glutamate, lysine, and threonine. Corynebacterium glutamicum is advantageous for use as an industrial strain due to simple growth conditions, a stable genome structure, and no environmental damage. Corynebacterium glutamicum is an aerobic bacterium, which stops metabolic processes except for basal metabolic process for energy generation when its oxygen supply is interrupted or under oxygen-deficient conditions thereby resulting in the production of lactic acid, acetic acid, succinic acid, and the like for energy generation.
Tricarboxylic acid (TCA) cycle is a metabolic pathway to generate energy and intermediate metabolites in biological species. The intermediate metabolites of the TCA cycles are used to synthesize useful chemical materials via other metabolic processes. Succinic acid is dicarboxylic acid used as a source material for biodegradable polymers, medicines, and cosmetics. Most industrially available succinic acids are synthesized from n-butane and acetylate originating from crude oil or liquefied natural gas. Only a small amount of succinic acid for use in special purposes such as for medicines or foods is produced via fermentation using microorganisms.
In general, chemical synthetic processes may require depletable fossil sources as basic materials and produce a large quantity of harmful byproducts. Therefore, there is a need for microorganisms capable of efficiently producing succinic acid, even by conventional methods, or a method of producing such microorganisms to overcome the significant drawbacks of conventional chemical synthetic processes.